Successive Pad Assignment for Minimizing Supply Voltage Drop

Takashi SATO  Masanori HASHIMOTO  Hidetoshi ONODERA  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E88-A   No.12   pp.3429-3436
Publication Date: 2005/12/01
Online ISSN: 
DOI: 10.1093/ietfec/e88-a.12.3429
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
Category: Power/Ground Network
Keyword: 
successive pad assignment (SPA),  incremental matrix inversion (IMI),  voltage drop,  power distribution network,  

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Summary: 
An efficient pad assignment methodology to minimize voltage drop on a power distribution network is proposed. A combination of successive pad assignment (SPA) with incremental matrix inversion (IMI) determines both location and number of power supply pads to satisfy drop voltage constraint. The SPA creates an equivalent resistance matrix which preserves both pad candidates and power consumption points as external ports so that topological modification due to connection or disconnection between voltage sources and candidate pads is consistently represented. By reusing sub-matrices of the equivalent matrix, the SPA greedily searches the next pad location that minimizes the worst drop voltage. Each time a candidate pad is added, the IMI reduces computational complexity significantly. Experimental results including a 400 pad problem show that the proposed procedures efficiently enumerate pad order in a practical time.